/*********************************************************************
 * Copyright (C) 2002 Andrew Khan
 * <p>
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * <p>
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * <p>
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ***************************************************************************/

package jxl.biff.formula;

import java.util.Stack;

/**
 * An operator is a node in a parse tree.  Its children can be other
 * operators or operands
 * Arithmetic operators and functions are all considered operators
 */
abstract class Operator extends ParseItem {
    /**
     * The items which this operator manipulates. There will be at most two
     */
    private ParseItem[] operands;

    /**
     * Constructor
     */
    public Operator() {
        operands = new ParseItem[0];
    }

    /**
     * Tells the operands to use the alternate code
     */
    protected void setOperandAlternateCode() {
        for (int i = 0; i < operands.length; i++) {
            operands[i].setAlternateCode();
        }
    }

    /**
     * Adds operands to this item
     */
    protected void add(ParseItem n) {
        n.setParent(this);

        // Grow the array
        ParseItem[] newOperands = new ParseItem[operands.length + 1];
        System.arraycopy(operands, 0, newOperands, 0, operands.length);
        newOperands[operands.length] = n;
        operands = newOperands;
    }

    /**
     * Gets the operands for this operator from the stack
     */
    public abstract void getOperands(Stack s);

    /**
     * Gets the operands ie. the children of the node
     */
    protected ParseItem[] getOperands() {
        return operands;
    }

    /**
     * Gets the precedence for this operator.  Operator precedents run from
     * 1 to 5, one being the highest, 5 being the lowest
     *
     * @return the operator precedence
     */
    abstract int getPrecedence();

}
